Re: [patch] possible SMP races all over the place in wait_event interface

[David S. Miller]

   Date: Tue, 24 Aug 1999 05:56:34 -0400 (EDT)
   From: Ingo Molnar <[EMAIL PROTECTED]>

   instead of:

                   current->state = TASK_INTERRUPTIBLE;
   +               mb();

   shouldnt we do:

   +            xchgl(&current->state, TASK_INTERRUPTIBLE);

   This 'merges' the barrier and the write. Or rather, in asm-i386 we could
   do something like: 

   #define set_mb(addr,val) xchgl(addr,val)

   and then use set_barrier().

Sure, but it costs ~8 instructions instead of 2 on ll/sc architectures.

Later,
David S. Miller
[EMAIL PROTECTED]
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